Preloaded cam follower



Feb. 21, 1967 R. E. GEESON 3,304,791

PRELOADED CAM FOLLOWER Filed Jan. 19, 1965 4 Sheets-Sheet l I n venforJaZerZ Evzeai 665mm ttorney J Feb. 21, 1967 R. E. GEESON PRELOADED CAMFOLLOWER 4 Sheets+$heet 2 Filed Jan. 19, 1965 I nvenlor 1 0561"? 1' 7!PS2 'eefayb Feb. 21, 1967 R. E. GEESON 3,304,791

PRELOADED CAM FOLLOWER Filed Jan. 19, l965 4 Sheets-Sheet 5 DID I nvenlor JPab r-f Z'rnaff 66am Feb. 21, 1967 E. GEESON 3,3

PRELOADED CAM FOLLOWER Filed Jan. 19, 1,965 4 Sheets-Sheet 4 InvenlorIzabel"? 1772652 fleejaw tlorrzey United States Patent 3,394,791PREILGADED CAM FOLLUWER Robert Ernest Geeson, Croydon, England, assignorto The Metal Box Company Limited, London, England, a British companyFiled Jan. 19, 1965, Ser. No. 4266M Claims priority, application GreatBritain, Jan. 28, 1964, 3,659/64 7 Claims. (CI. 74-54) This inventionrelates to operating mechanism for effecting reciprocating oroscillating movements and in particular to such mechanisms as arecontrolled positively in both directions by means of cams.

With mechanisms of the kind above mentioned, particularly for high speedoperation, it is desirable to eliminate backlash and thereby impact dueto taking up the clearance at the commencement of each cycle. The kindsof cams usually employed for this purpose are thread cams, grooved camsof face type or of drum type, and dual disc cams. Such cams are usuallyemployed with roller-type followers, and whereas statically backlash maybe taken up by making the cams an exact fit between two roller-typefollowers, for dynamic conditions an interference fit must be employedto eliminate backlash up to the full load rating of the mechanism.

If such interference fits make use only of the inherent elasticity ofthe components, the rate of variation of the pie-load is high for smallincrements of variation of fit. This can give rise to variations in thepre-load during operation of the mechanism, due to the effect of minorinaccuracies in manufacture of the cams or changing temperatureconditions which cause differential expansion of the parts.

It is a main object of the present invention to overcome suchdifiiculties whilst retaining the advantages of preloaded followers.

According to the invention there is provided an operating mechanismwhich includes cam means engaged by a pair of follower rollers arrangedto reduce backlash and impact due to the taking up of clearance at thecommencement of a cycle, wherein one of the rollers is arranged forconcentric rotation about the axis of a stud is rotatable about a secondstud carried by the supporting member and is movable laterally of theaxis of the sec- 0nd stud against the action of a spring exerting apreloading force along the direction of the axis of the second stud, thearrangement being such that if a force exerted against the second rollerin a direction radial to the axis of the second stud exceeds the valueof the preloading force the second roller is displaced fromconcentricity with the axis of the second stud until a state ofequilibrium exists between the radial force and the axial force exertedby the spring.

In one embodiment of the invention the second roller comprises anannular cam-engaging member, a race coaxial with the second stud andmounted thereon for sliding movement axially thereof, said race having aconical bearing track located within the annular camengaging member,rolling elements housed in an annular track formed in the cam-engagingmember for rolling engagement with the conical bearing track, and apreloaded spring operable to urge the conical bearing track of the raceinto engagement with the rolling elements. In another embodiment of theinvention the second roller comprises an annular cam-engaging member, apair of races co-axial with the second stud and mounted thereon, saidraces each having a conical bearing track located within saidcam-engaging member and at least one of the races being slidable axiallyof the second stud and urged towards the other race by a pre-loadedspring, and rolling elements housed in an annular track formed in thecam-engaging member for rolling engagement with said conical bearingtracks.

The rolling elements may consist of rollers alternate ones of which aredisposed with the axes of rotation thereof at right angles one to theother.

In order that the invention may be clearly understood some embodimentsthereof will now be described, by way of example, with reference to theaccompanying drawings, in which:

FIGURE 1 illustrates a part of a cam seaming mechanism having operatingmechanism according to the invention applied thereto,

FIGURE 2 illustrates, partly in section, a part of the mechanism shownin FIGURE 1,

FIGURE 3 is a side elevation of a spring embodied in the mechanism ofFIGURE 2,

FIGURE 4 is a plan of FIGURE 3,

FIGURE 5 diagrammatically illustrates an alternative embodiment of theoperating mechanism,

FIGURE 6 is a sect-ion through a cam follower embodied in the mechanismof FIGURE 5,

FIGURE 7 is a section through a cam follower al ternative to that shownin FIGURE 6, and

FIGURES 8 to 15, in elevation and plan, illustrate alternative forms ofspring which can be used in mechanism according to the invention.

FIGURE 16 is a fragmentary sectional view of the mechanism of FIGURE 1,wherein balls are illustrated as being the rolling elements.

In the drawings like references refer to like or similar parts.

Referring to FIGURES 1 to 4, a seaming roll I is supported by one arm 2of a pair of arms secured to a stub shaft 3, FIGURE 1, for rockingmovement about the axis of shaft 3 in a seaming roll support 4 rotatableabout the axis of a chuck 5; the other arm 6 of the pair supports a pairof roller cam followers 7, 8 which cooperate respectively with cams 9,It) to cause the seaming roll to follow a path which conforms to thecontour of the chuck, and to apply seaming pressure to the seaming roll.

The roller follower 7 is arranged for concentric rotation about the axisof a stud 11, FIGURE 2, carried by a supporting member which, in thisembodiment of the invention, consists of a spindle 12. The secondfollower roller 8 is rotatable about a second stud 13 carried by thesupporting member 12, and, as described below, is movable laterally ofthe axis of the second stud 13 against the action of springs 14 exertinga pro-loading force along the direction of the axis of the second stud13, the arrangement being such that if a force exerted against theroller 8 in a direction radial to the axis of the second stud 13 exceedsthe value of the preloading force the second roller 3 is displaced fromconcentricity with its axis until a state of equilibrium exists betweenthe radial force and the axial force exerted by the springs 14.

The second roller 8 comprises an annular cam-engaging member 15 and apair of races 16, 17 co-axial with the second stud 13 and mounted on thestud 13. The races 16, 17 respectively have conical bearing tracks 18,

19 located within the cam-engaging member 15 and the '3 ones of whichare disposed with the axes of rotation thereof at right angles one tothe other. The number of rollers 21 is an even number.

If desired instead of both races 16, 17 being slidable axially of thestud 13 one may be constrained against such movement in which eventa-spring 14 will engagev only the one race which is free to slideaxially of the stud 13.

As shown in FIGURES 2 to 4 the spring 14, or each spring 14, is a knownform of slotted tube spring, see FIGURES 3 and 4, and sliding movementof the race or races is constrained by the force exerted by the springor springs, thus the races are caused to close on the rolling elements21.

It will be understood that if the spring, or springs, is deflected withthe races 16, 17 in position a pre-load will be exerted upon the rollingelements 21 and that if a radial force .is exerted against'the member 15which exceeds the value of the pre-load, then the member 15 will beforced off-centre to the stud 13 until equilibrium is maintained betweenthe radial force and the axial force exerted by the spring 14.

The roller 8 can, therefore, be arranged so that its intended operatingposition, when assembled to the cam in co-operation with thenon-yielding follower roller 7, is with the yieldable roller 8 displacedfrom concentricity with the stud 13 by an amount equal to one half ofthe total movement permissible by virtue of the proportions of theroller 8, and so that in this position the force exerted by the spring14 is equal to the required pre-load on the cam surface.

It follows that variations of the cam surface due to inaccuracies orvariation in relative position of the two follower rollers 7, 8 due todeflections or expansion will vary the degree of eccentricity betweenthe yieldable follower roller 8 and its stud 13. It also follows thatsuch variations will cause variations of the pre-load dependent upon therate of the spring 14, and that such variations of the pre-load will beof minor character compared to those existing with two non-yieldablefollower rollers as used prior to the invention, provided that suchvariations of eccentricity do not permit the. yieldable roller 8 toreach the point of concentricity or the point at which eccentricmovement must be restrained to prevent rubbing contact of the roller 8with non-rotating components.

FIGURE 5 illustrates diagrammatically an alternative embodiment of theinvention in which the follower rollers 7, 8 co-oper-ate with oppositesides of the track 22 of a track cam. The rollers 7, 8 are mounted onstuds which extend laterally from a supporting member 12 which is to bereciprocated by the cam. In this embodiment of the invention the roller8 includes only one race 16 and this is slidable axially of its stud 13and is urged towards the rolling elements 21 by the spring 14. FIGURE 7illustrates an alternative form of the roller 8 shown in FIGURE 6.

FIGURES 8 to 15 illustrate known kinds of springs which can be used asalternatives to the spring shown in FIGURES 3 and 4. FIGURES 8 and 9illustrate a helical compression spring 14a, FIGURES 10 and 11 athreepoint cup spring 14b, FIGURES 12 and 13 a Belleville spring 140,and FIGURES 14 and 15 a rubber ring 1411.

FIGURE 16 illustrates an alternative embodiment to that of FIGURE 2,wherein balls 22 are the rolling elements in engagement with the bearingtracks 18, 19 and 20.

, 4 I claim: 1. An operating mechanism which includes cam means. engagedby a pair of follower rollers arranged to reduce: backlash and impactdue to the taking up of clearance at the commencement of a cycle, asupporting membercarrying first and second studs; one of: the rollersbeing arranged for concentric rotation about the axis of the first studcarried by the supporting member and the second roller being rotatableabout the second stud carried by the supporting member; mounting meansincluding a spring for facilitating the movement of said second rollerlaterally of the axis of the second stud against the action of saidspring; said spring providing means for exerting a pre-loading forcealong the direction of the axis of the second stud whereby if a forceexerted against the second roller in a direction radial to the axis ofthe second stud exceeds the value of the pre-loading force the secondroller is displaced from concentricity with the axis of the second studuntil a state of equilibrium exists between the radial force and theaxial force exerted by the spring.

2. Mechanism according to claim 1, wherein the sec ond roller comprisesan annular cam-engaging member, a race oo-axial with the second stud andmounted thereon for sliding movement axially thereof, and rollingelements; said race having a conical bearing track located within theannular cam-engaging member for rolling engagement with said elements;said preloaded spring being operable to urge the conical bearing trackof the race into engagement with the rolling elements.

3. Mechanism according to claim 2, wherein the rolling elements consistof rollers alternate ones of which are disposed with the axes ofrotation thereof at right angles one to the other.

4. A mechanism according to claim 2 wherein said rolling elements areballs.

5. Mechanism according to claim 1, wherein the second roller comprisesan annular cam-engaging member, a pair of races co-axial with the secondstud and mounted thereon, said races each having a conical bearing tracklocated within said cam-engaging member and at least one of the racesbeing slidable axially of the second stud and urged towards the otherrace by said pro-loaded spring, and rolling elements housed in anannular track formed in the cam-engaging member for rolling engagementwith said conical bearing tracks.

' 6. Mechanism according to claim 5, wherein the roll- 'ing elementsconsist of rollers alternate ones of which are disposed with the axes ofrotation thereof at right angles one to the other.

7. A mechanism according to claim 5 wherein said rolling elements areballs.

References Cited by the Examiner UNITED STATES PATENTS MILTON KAUFMAN,Primary Examiner.

FRED C. MATTERN, IR. Examiner.

D. H. THIEL, Assistant Examiner.

1. AN OPERATING MECHANISM WHICH INCLUDER CAM MEANS ENGAGED BY A PAIR OFFOLLOWER ROLLERS ARRANGED TO REDUCE BACKLASH AND IMPACT DUE TO THETAKING UP OF CLEARANCE AT THE COMMENCEMENT OF A CYCLE, A SUPPORTINGMEMBER CARRYING FIRST AND SECOND STUDS; ONE OF THE ROLLERS BEINGARRANGED FOR CONCENTRIC ROTATION ABOUT THE AXIS OF THE FIRST STUDCARRIED BY THE SUPPORTING MEMBER AND THE SECOND ROLLER BEING ROTATABLEABOUT THE SECOND STUD CARRIED BY THE SUPPORTING MEMBER; MOUNTING MEANSINCLUDING A SPRING FOR FACILITATING THE MOVEMENT OF SAID SECOND ROLLERLATERALLY OF THE AXIS OF THE SECOND STUD AGAINST THE ACTION OF SAIDSPRING; SAID SPRING PROVIDING MEANS FOR EXERTING A PRE-LOADING FORCEALONG THE DIRECTION OF THE AXIS OF THE SECOND STUD WHEREBY IF A FORCEEXERTED AGAINST THE SECOND ROLLER IN A DIRECTION RADIAL TO THE AXIS OFTHE SECOND STUD EXCEEDS THE VALUE OF THE PRE-LOADING FORCE THE SECONDROLLER IS DISPLACED FROM CONCENTRICITY WITH THE AXIS OF THE SECOND STUDUNTIL A STATE OF EQUILIBRIUM EXISTS BETWEEN THE RADIAL FORCE AND THEAXIAL FORCE EXERTED BY THE SPRING.